Volvo: S 80 check engine light, false alarms, favorite shop

Question
Our 99 S 80 has had many problems with check engine lights. Today I was driving and the light came on, as well as the message "drive slowly, urgent service needed" I pulled over and checked fluids and all were okay. The good repair shop was booked until next week!! The car handles okay except for sluggish and rough running when cold. Is it safe to drive in this state? We have had many, many false alarms with the warning lights. Should we bite the bullet and head for the dealer?  

Answer
Rob,
A better question would be since the car does exhibit sluggishness and runs rough are you prepared to repair the car if further damage is done, just because the dealer is not top on your list? One can not tell without reading the fault code how great the urgency is. If my favorite shop was too busy I would park the car.